skillzilla

iTrader: (1)

I'm having this bad electrical issue and think I might have tracked it down to the ignition switch itself, but wanted to get some opinions.

So, basically anything that requires the key to be in ACC or ON or START doesn't work. Dome/door lights are good, headlights are good, hazards are good, but no radio, ECU power, starter signal, etc.

Using a voltmeter I checked continuity in the switch itself and each key position gave me continuity on the correct wire out of the switch. I also checked that the power supply to the ignition switch is good, and it does have 12V. So, My key switch has incoming 12V constant, and switches voltage correctly based on key position. So, at first I was hesitant to think it was the switch since these don't go out very often I'm sure, so I kept looking into it.

Still, my ECU is not getting power and I dont have a start signal. At the main relay, the black/white wire coming from the 15A engine fuse (the signal wire for the relay) gets voltage when the key is turned to ON, but it only gets less than a volt. If I pull the 15A Engine fuse it gets no power at all, as is expected.

Looking at the wiring diagram for my car (S5 TII), it looks as though the black/white wire coming from the ignition switch goes to the interior fuse box and provides current to a number of fuses, the main ones Im looking at being Antenna (signal for the Starter relay) and Engine (signal for the Main relay). Both of these relays are not functional.

Am I pretty safe to assume the problem exists somewhere between the key being put in the ignition and the fuse box, since both relays are not working?

If I test voltages at the ignition switch (testing on the exposed metal bits on the side), I never see more than .5 volts on any lead at any key position, except for one lead that has constant 12V. This has me thinking the switch itself is bad internally, and not giving a good connection to provide enough power to switch the relays over. So, even though the switch itself is working correctly, the voltage it is passing is way too low.


Any help is appreciated., thanks peeps!!

skillzilla

iTrader: (1)

Oh, forgot to mention i have not tested voltages at the fuse box in the Engine and Anrtenna slots. Will be doing that later today to see if the low voltages exist there also, then will move back closer to the key if so.

satch

iTrader: (1)

There are different causes for your problem but they basically relate to the voltage from the battery not making it to the ignition swtch. There is a cable that goes from the positive terminal of the battery to the engine fuse box and is connected to the side closest to the battery. Check this Black cable for voltage. If there is voltage on that cable it then passes the voltage through the fuse box and it comes out of various wires and the wire you want to focus on is another Black cable that comes off the other side of this fuse box for voltage. If there is not voltage on this Black wire then either the Main fuse ( main fuse is screwed into place and does not just pull out) is blown or there is a faulty connection at the fuse box. If there is voltage on the Black wire coming out the back of the fuse box then follow that wire downwards as it leads to a connector within a foot or so of the fuse box. Make sure this connection is solid and check for voltage on the side of the connector that the Black wire plugs into. If there is voltage on the other side of the connector then check under the dash near the steering wheel between the steering column and the driver side door and there you will find the wires that plug into the ignition switch located just to the side of the steering column. One of these plugs has two wires colored Black/White and the other wire being solid Black. The solid Black is the wire that you have been checking since it came from the battery. Make sure it has voltage and that it is connected securely to the ignition switch harness. This Black wire has constant voltage all the way from the battery so no key is necessary to check for voltage.

skillzilla

iTrader: (1)

I have mods all over the place that are far from OEM but I know exactly what youre referring to. Thanks for the tips definitely.

I do have power on the black wire coming from the Main fuse. The 100A is good, and I also have BTN power (dome light works) and power for the headlights. So, everything leading up to and including the power block under the hood is good to go.

I also have 12V constant at the black wire where it leads to the ignition switch. So, the switch itself has a good power source, and my troubles seem to be either at the switch itself or between the switch and the fuse box.

satch

iTrader: (1)

Then make sure the other plugs connected to the ignition switch are secure as well. The B/W wire is for the IG1 fuses in the interior fuse box so see if there is voltage coming out of the B/W wire from the ignition switch plug as it makes its way to the interior fuse box. If there is then it isn't connected to the fuse box properly. If there isn't voltage coming from the B/W wire w/key to on as it leaves the ignition switch then your switch is problematic.

skillzilla

iTrader: (1)

Thats what I am going to check today. Crappy part is the 12V power source for the ignition switch is on the same 2-wire connector as the black/white wire that goes to the fuse box, so I can't disconnect it to test for power Will have to back-probe the connector and it got too dark out last night so I gave up for the night.

But, all connections for the switch are secure, that I am sure of. Once I test voltage on the black/white wire and at the fuse box I will hopefully see an issue.

satch

iTrader: (1)

If back probing is not your cup of tea and it very well might not be then you could ***** the wire with a pin and source the pin for voltage. Chances are it is your switch as it would be unlikely that the IG1, IG2 and ACC wires are disconnected from the fuse box.

skillzilla

iTrader: (1)

Thats an idea, thanks man. Would rather do that than try shoving a huge probe into these brittle plastic connectors, that has turned out bad before.